Merge branch 'stable-2.16'

* stable-2.16:
  Upgrade bazlets to latest stable-2.16 to build with 2.16.6 API
  Add the standard LICENSE file
  Documentation: Fix the in-tree bazel test command
  Start dockerized postgres server in junit test using testcontainers
  PostgresQueueTest#testList: Tolerate up to 1s skew in queued time stamp
  Upgrade bazlets to latest stable-2.15 to build with 2.15.11 API

Change-Id: I7829c03bc605de0b5fd0c954dd74b13c3f08197b